A galvanic isolator provides a means for moving a signal from one electrical circuit to another electrical circuit in a control system when the two electrical circuits must otherwise be electrically isolated from one another. Usually the two electrical circuits operate at different voltages, and thus, must be electrically isolated. For example, consider an application in which a 5V battery powered controller board is configured to control a motor circuit operating at 240V. In this example, it is essential to electrically isolate the 240V motor circuit from the 5V controller circuit, while permitting the 5V controller circuit to send or receive signals from the 240V motor circuit. In this type of application, an isolator may be used to provide voltage and noise isolation, while permitting the information exchange between the two circuit systems. Opto-isolator, also known as optocoupler, is one of the most commonly used galvanic isolators.
Generally, an opto-isolator comprises an optical emitter and an optical receiver. Over time, degradation may occur and optical signals emitted from the optical emitter may become weak, and eventually the optical emitter may fail to function. For many control systems, failure of such optical parts may be vulnerable and may be dangerous as the control systems may be relying on the optical signals to control fast moving motors or machinery parts. It may be desirable to take preventive steps to replace the parts before complete failure, or to address the degradation to prolong the lifetime of the opto-isolators.